This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-012053, filed Jan. 21, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of forming a coating film by a so-called xe2x80x9cscan coating methodxe2x80x9d, to a method of manufacturing a semiconductor device, and to a coating solution.
2. Description of the Related Art
Semiconductor devices are manufactured through the formation of a coating film or films, such as an interlayer insulating film or a resist film, above a semiconductor substrate. It has been customary to use a spin coating method for forming such a film on the semiconductor substrate. In the spin coating method, a coating solution is dripped onto a substrate while rotating the substrate so as to centrifugally form uniformly a film of the coating solution on the substrate. In the spin coating method, however, the coating solution is scattered by the rotation of the substrate, resulting in loss of the coating solution. Also, where the substrate has a stepped portion, an additional problem is brought about that the coating film formed on the stepped portion is poor in the surface smoothness.
Under the circumstances, a so-called xe2x80x9cscan coating methodxe2x80x9d is being studied in recent years in an attempt to improve the utilization rate of a coating solution and to improve the smoothness in the surface of the coating film when the substrate having a stepped portion is coated with the coating solution. In the scan coating method, a coating solution is discharged through a nozzle onto a substrate while relatively moving the nozzle and the substrate so as to form a continuous coating solution film. Then, the solvent is removed from the coating solution film, forming a desired coating film.
Nowadays, the coating solution used in the spin coating method is often diverted to the scan coating method. In this case, it is possible to improve the uniformity of the coating film on the stepped portion of the substrate, compared with the spin coating method. However, a problem arises that the scan coating method is inferior in general to the spin coating method in the in-plane uniformity in the thickness of the formed coating film. It should also be noted that, in the scan coating method, it is necessary for the liquid lines discharged onto the substrate in the form of, for example, parallel lines or a spiral line to be leveled so as to be joined to each other on the substrate such that the substrate may be covered with a single continuous liquid film. In order to decrease the coating amount of the coating solution, it is required for the coating solution discharged onto the substrate to be leveled more efficiently.
According to a first aspect of the present invention, there is provided a method of forming a coating film, comprising:
forming a coating solution film on a substrate by discharging a coating solution comprising a coating film-forming material dissolved in a solvent onto the substrate through a nozzle while relatively moving the nozzle and the substrate, the coating solution containing a low vapor pressure solvent having a vapor pressure of less than 1 Torr (133.322 Pa) at room temperature; and
removing the solvent contained in the coating solution film.
According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising forming at least one coating film on a semiconductor substrate, wherein the coating film is formed by a method of forming a coating film according to the first aspect of the present invention.
Further, according to a third aspect of the present invention, there is provided a coating solution for forming a coating film by a scan coating method, the coating solution containing a low vapor pressure solvent having a vapor pressure of less than 1 Torr (133.322 Pa) at room temperature.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.